This invention relates to regulated deflection circuits.
A typical circuit in switching regulators for television receiver deflection circuits includes an SCR regulator switch in series with the unregulated DC voltage and the regulated B+ input voltage. Also series coupled is a flyback transformer winding and a current limiting fixed value inductor.
During a variable turn-on instant within trace, for example, the SCR is forward biased into conducting input current. The input current reaches a maximum at the end of trace and decreases to zero during retrace as the retrace pulse voltage causes the input current to decrease and commutate off the SCR. The SCR remains nonconductive until the aforementioned turn-on instant occurs in the next deflection cycle. Regulation is achieved using SCR gate pulse control circuitry which varies the turn-on instant of the SCR. Such switching regulators are relatively costly in that an active semiconductor device and a relatively complicated control circuitry are required.
Some regulators for thyristor deflection circuits include both a forward input current and a return current path from the unregulated DC terminal to the thyristor deflection circuit. A transductor is then placed in one of the current paths for regulating one of the forward input and return currents. Such circuits are relatively dissipative as both forward and return currents flow each deflection cycle.